(1) Field of the Invention
This invention relates to automated methods of deflashing articles. More particularly, the invention relates to automated methods of deflashing molded urethane articles using a blast of particles.
(2) Description of Related Art
Molded articles made from two or more mold pieces collect excess material, called flash, along the seams where the mold pieces meet. The flash is undesirable because it hinders proper alignment of the parts and it is not aesthetically pleasing.
Currently, there are two types of methods for removing the flash, or, in other words, deflashing molded articles. The first method is the manual removal of the flash. This method is undesirable because it slows production and it is labor intensive; both of which render this method cost inefficient.
The second method of deflashing a molded article is an automated procedure. This is typically done by projecting an object or objects at the flash of an article with sufficient inertia to deflash the molded article. U.S. Pat. Nos. 3,628,295 and 3,696,565 to Curtiss and Claeys, respectively, both disclose methods for deflashing articles by projecting small particles, glass beads and rubber particles, respectively, at the article having the flash.
The usage of glass beads is not acceptable in instances where the finish of the molded article would be damaged due to the hardness of the glass beads. On the other hand, the rubber particles are not acceptable due to the elasticity of rubber when impinged upon molded articles which are semi-rigid. Also, rubber particles tend to gel when they heat up resulting in particles that are difficult to project and/or reuse.
U.S. Pat. No. 3,396,495 to Voss, issued Aug. 13, 1968 discloses a method for deflashing black phenolic plastic which is a hard plastic. The flash created when molding with black phenolic plastic is removed by projecting acrylic plastic at the black phenolic plastic article. More specifically, Lucite Plastic Compound #29 or #47, as marketed by the DuPont Company, Inc., is the acrylic plastic used. The acrylic plastic, however, is very hard and will damage articles of softer material.
U.S. Pat. No. 3,090,166 to Straub, issued May 21, 1963 discloses a polishing method and device for polishing hard surfaces. The method includes the steps of projecting soft particles at hard surfaces, such as metal. The method, however, is incapable of deflashing any of the articles because the articles are made of materials which are unaffected by the soft particles.
A method of automatically deflashing molded articles is needed wherein particles are rigid enough to deflash semi-rigid articles properly and, yet, soft enough so as not to harm the molded article.